Rulers

About rulers

Rulers help you position images or
elements precisely. When visible, rulers appear along the top and
left side of the active window. Markers in the ruler display the
pointer’s position when you move it. Changing the ruler origin (the
(0, 0) mark on the top and left rulers) lets you measure from a
specific point on the image. The ruler origin also determines the
grid’s point of origin.

To show or hide rulers, choose View > Rulers.

Change a ruler’s zero origin

(Optional) Choose View >
Snap To, then choose any combination of options from the
submenu. This snaps the ruler origin to guides, slices, or document bounds.
You can also snap to the grid.

Position the pointer over the intersection of the rulers
in the upper-left corner of the window, and drag diagonally down
onto the image. A set of cross hairs appears, marking the new origin
on the rulers.

Note:

You can hold down Shift as you drag to
make the ruler origin snap to the ruler ticks.

To reset
a ruler’s origin to its default value, double-click the upper-left
corner of the ruler.

Dragging to create new ruler origin

Change the unit of measurement

Do one of the following:

Double-click a ruler.

(Windows) Choose Edit > Preferences >
Units & Rulers, or right-click the ruler and then choose a new
unit from the context menu.

(Mac OS) Choose Photoshop >
Preferences > Units & Rulers, or Control-click the
ruler and then choose a new unit from the context menu.

For Rulers, choose a unit of measurement.

Note:

Changing the units on the Info panel automatically
changes the units on the rulers.